The Dev in DevOps stands for development and Ops stands for operations. DevOps tries to minimize the gap between development and operations. Agile software development has minimized the gap and improved collaboration between requirements analysis, testing, and development, whereas, the DevOps movement encourages collaboration between development and operations.
The exact definition of DevOps varies from business to business, but, in essence, DevOps is all about minimizing the challenges of shipping, rapidly iterating, and securing software applications.